Yes, your router must connect to a modem to reach the internet
A modem is the device that converts the signal from your internet service provider into data your devices can use. A router takes that data and broadcasts it wirelessly (or through cables) to your devices. Without the modem, the router has nothing to broadcast. Without the router, you could still use the internet, but only on devices plugged directly into the modem with an ethernet cable, and only one at a time on most home setups.
The modem connects to your ISP's network. The router connects to the modem. Your devices connect to the router. That chain is how home internet works. You cannot skip the modem and go straight from your ISP to the router.
Key Takeaways
- The modem receives the internet signal from your ISP; the router distributes it to your devices, so both are necessary for wireless internet at home.
- You can use the internet with only a modem if you plug devices directly into it with ethernet cables, but you cannot use only a router without a modem.
- Some ISPs rent you a combined modem-router unit, but it still performs both functions even if they are in one box.
- The modem must be powered on and connected to your ISP's line before the router will have any internet to share.
What happens if you unplug the modem but leave the router on
The router will still turn on and broadcast a wireless signal, but that signal will not connect to the internet. Your devices will see the network name and may connect to it, but they will not be able to load websites, send email, or stream video. The router has no data to send because the modem is not receiving anything from your ISP.
This is a common source of confusion when troubleshooting. A working router does not mean you have working internet — it only means the router is powered and broadcasting. The modem is what determines whether you actually have internet access.
Modem-router combo units and why they still need both functions
Many ISPs provide a single box that contains both a modem and a router. Comcast's Xfinity boxes and similar devices from other providers work this way. Even though they are in one physical unit, the modem part and the router part are still doing their separate jobs: one receives the signal from the ISP, and the other broadcasts it to your devices.
You still cannot remove the modem function and keep only the router function. The combo unit is straightforward a convenience — it saves space and one power outlet. The underlying requirement remains the same: you need a modem to connect to your ISP, and you need a router (or a combo unit) to share that connection wirelessly.
When you might use a modem without a router
If you have only one device that needs internet, or if you are in a temporary setup, you can plug a single computer or device directly into the modem using an ethernet cable. The modem will provide internet to that device without any router involved. This is common in offices, server rooms, or when setting up a new computer for the first time.
However, most home users need a router because they have multiple devices — phones, tablets, laptops, smart TVs, smart speakers. A modem typically has only one or two ethernet ports, and it does not broadcast wireless signal. A router solves both problems by taking the modem's connection and sharing it among many devices, both wired and wireless.
How to check if your modem and router are connected properly
Look at the back of your modem. You should see a cable labeled "Internet," "WAN," or "From ISP" that connects to your wall outlet or the line from outside. You should also see an ethernet cable running from the modem to the router (or to a combo unit). If that cable is unplugged or loose, your router will not have internet even if the modem is working.
On the modem itself, look for lights. Most modems have a light that indicates internet connection — it is usually labeled "Internet," "Online," or "WAN." If that light is off or red, the modem is not receiving a signal from your ISP, and no router connected to it will have internet. If the light is on and green (or solid), the modem is working, and the problem is likely with the router or the cable between them.
What to do if your router is connected but you have no internet
First, check that the ethernet cable between the modem and router is plugged in firmly on both ends. Unplug it and plug it back in. Then check the modem's internet light. If it is off or red, restart the modem by unplugging it for 30 seconds, then plugging it back in. Wait two to three minutes for it to fully restart.
If the modem's light comes back on and is green, restart the router the same way. If the modem's light stays off or red after restart, the problem is with your ISP's connection, not your equipment. Contact your ISP to report that the modem is not connecting to their network. If the modem light is green but you still have no internet on your devices, the problem is likely with the router or the cable between them.
Frequently Asked Questions
Can I use a router without a modem?
No. A router needs an internet source to share. Without a modem connected to your ISP, the router has nothing to broadcast. You would have a wireless network, but it would not connect to the internet.
Can I use a modem without a router?
Yes, but only for one device at a time. You can plug a computer directly into the modem with an ethernet cable and use the internet. Most homes need a router because they have multiple devices and want wireless connectivity.
Do I need to restart my modem and router in a specific order?
Restart the modem first and wait for it to fully restart (two to three minutes). Then restart the router. This ensures the modem has reconnected to your ISP before the router tries to connect to the modem.
What if my ISP gave me a combo unit — do I still need both parts?
Yes. The combo unit contains both a modem and a router in one box. You cannot remove one function and keep the other. Both are necessary for your devices to have wireless internet.
Why does my router show a strong signal but I cannot load websites?
A strong router signal means the router is broadcasting, but it does not mean the modem is connected to your ISP. Check the modem's internet light. If it is off or red, the modem is not receiving a signal from your ISP, and no device will be able to load websites even though they are connected to the router.